Flow Models in Boundary-Layer Stall Inception

Sandborn, V. A.; Kline, S. J.

doi:10.1115/1.3658953

Cited by 72 publications

(18 citation statements)

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“…The line h = 1.5Λ was discussed by Simpson (1989), who stated that the data of Perry & Schofield (1973) supported the hypothesis that this characterized a path for detaching flow. Another line is h = 1/(2 − Λ) proposed by Sanborn & Kline (1961). They suggested that at a given Λ, h greater than this value would indicate appreciable intermittent backflow.…”

Section: H-λ Relationmentioning

confidence: 98%

Large-eddy simulation of separation and reattachment of a flat plate turbulent boundary layer

2015

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We present large-eddy simulations (LES) of separation and reattachment of a flat-plate turbulent boundary-layer flow. Instead of resolving the near wall region, we develop a two-dimensional virtual wall model which can calculate the timeand space-dependent skin-friction vector field at the wall, at the resolved scale. By combining the virtual-wall model with the stretched-vortex subgrid-scale (SGS) model, we construct a self-consistent framework for the LES of separating and reattaching turbulent wall-bounded flows at large Reynolds numbers. The present LES methodology is applied to two different experimental flows designed to produce separation/reattachment of a flat-plate turbulent boundary layer at medium Reynolds number Re θ based on the momentum boundary-layer thickness θ. Comparison with data from the first case at Re θ = 2000 demonstrates the present capability for accurate calculation of the variation, with the streamwise co-ordinate up to separation, of the skin friction coefficient, Re θ , the boundary-layer shape factor and a non-dimensional pressure-gradient parameter. Additionally the main large-scale features of the separation bubble, including the mean streamwise velocity profiles, show good agreement with experiment. At the larger Re θ = 11 000 of the second case, the LES provides good postdiction of the measured skin-friction variation along the whole streamwise extent of the experiment, consisting of a very strong adverse pressure gradient leading to separation within the separation bubble itself, and in the recovering or reattachment region of strongly-favourable pressure gradient. Overall, the present two-dimensional wall model used in LES appears to be capable of capturing the quantitative features of a separation-reattachment turbulent boundary-layer flow at low to moderately large Reynolds numbers.

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Section: H-λ Relationmentioning

confidence: 98%

Large-eddy simulation of separation and reattachment of a flat plate turbulent boundary layer

2015

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“…͑12͒ into Eq. ͑6͒ and clearing terms yields: (13) where the term involving ϪdP ϱ /dx has been cancelled by the U ϱ dU ϱ /dx term from Euler's equation for the external flow.…”

Section: Review Of the Castilloõgeorge Analysismentioning

confidence: 99%

Separation Criterion for Turbulent Boundary Layers Via Similarity Analysis

Castillo

Wang

George

2004

Journal of Fluids Engineering

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By using the RANS boundary layer equations, it will be shown that the outer part of an adverse pressure gradient turbulent boundary layer tends to remain in equilibrium similarity, even near and past separation. Such boundary layers are characterized by a single and constant pressure gradient parameter, Λ, and its value appears to be the same for all adverse pressure gradient flows, including those with eventual separation. Also it appears from the experimental data that the pressure gradient parameter, Λθ, is also approximately constant and given by Λθ=0.21±0.01. Using this and the integral momentum boundary layer equation, it is possible to show that the shape factor at separation also has to within the experimental uncertainty a single value: Hsep≅2.76±0.23. Furthermore, the conditions for equilibrium similarity and the value of Hsep are shown to be in reasonable agreement with a variety of experimental estimates, as well as the predictions from some other investigators.

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“…The integral properties corresponding to separation agree well with the separation criteria of Sandborn and Kline. 9 Downstream of the separation the outer region velocity profiles show some similarity and the chordwise development of the mean velocity is found to be reducible to a universal curve.…”

Section: Discussionmentioning

confidence: 95%